1. Field of the Invention
The present invention relates to an optical disc drive, and more particularly, to a tray guide mechanism that is easily inserted into and ejected from a narrow chassis of a slim optical disc drive.
2. Description of the Related Art
In general, an optical disc drive is an apparatus that is used to record or reproduce data to/from an optical recording medium such as a compact disc (CD) or a digital versatile disc (DVD) by irradiating light thereon. The optical disc drive is mainly used in a computer. Particularly, an ultra thin optical disc drive is required in a notebook-sized personal computer.
FIG. 1 is a view of an example of a conventional optical disc drive which is disclosed in Japanese Patent Laid-Open Publication No. Hei 9-223347. FIGS. 2 and 3 are views of right and left sides, respectively, of a tray guide mechanism of the optical disc drive of FIG. 1.
Referring to FIGS. 1 through 3, the conventional slim optical disc drive includes a housing 10 that is composed of a lower case 18 and an upper case 19, and a tray 12 that is inserted into and detached from the housing 10. A main base 16 is combined with the tray 12 and includes a spindle motor 26 that rotates a disc. The main base 16 also includes an optical pickup unit 23 that is used to reproduce data recorded on the disc, and a shift unit (not shown) that shifts the optical pickup unit 23 backward and forward in a radius direction of the disc. Therefore, the tray 12 may move in and out of the housing 10 together with the spindle motor 26 and the optical pickup unit 23.
The conventional optical disc drive also includes a tray guide mechanism which guides the tray 12 to move forward and backward as indicated by an arrow A–B shown in FIG. 1. The tray guide mechanism includes rail combiners 29 and 30 that are formed at sides of the tray 12, and sliding rails 31 and 32 that guide the rail combiners 29 and 30, and glide to engage with the rail combiners 29 and 30. The tray guide mechanism also includes fixing guides 33 and 34 that are firmly installed at both corners of the lower case 18 to support the sliding rails 31 and 32 which guide and glide the rail combiners 29 and 30.
As shown in FIG. 2, the sliding rail 31 moves along the fixed guide 33 in the A and B direction at the same time as the tray 12 moves out of the optical disc drive. When the tray 12 reaches a position where the disc may be exchanged with another disc, a protrusion 33b of a detent 33a of the fixed guide 33 fits into a hole 31b of the sliding rail 31 to prevent the sliding rail 31 from moving in an ejecting direction B.
As shown in FIG. 3, the sliding rail 32 moves along the fixed guide 34 in the A and B direction at the same time as the tray 12 moves out of the optical disc drive. When the tray 12 reaches a position where the disc may be exchanged with another disc, a protrusion 34b of a detent 34a of the fixing guide 34 fits into a hole 32b. As a result, the sliding rail 32 is prevented from moving further in the ejecting direction B.
Meanwhile, although not illustrated in the above described drawings, in the housing 10 and at a bottom of the tray 12 is installed a locking unit that locks the tray 12 in the housing 10. Also installed, is an ejector that allows the tray 12 to be ejected from the housing 10. As shown in FIG. 1, a front bezel 15 is attached to a front end of the tray 12, and includes an ejection switch part 14 that is pushed to operate an ejector that allows the tray 12 to move in and out of the optical disc drive.
When the disc is loaded into the optical disc drive having the above mechanism, the tray 12 is ejected from the housing 10, the disc is placed on the spindle motor 26, and then the disc is inserted into the housing 10. As a result, the locking unit operates to lock the tray 12 into the housing 10, and when the disc is unloaded from the optical disc drive, the ejection switch part 14 is pushed to operate the ejector to push the tray 12 out of the housing 10.
However, in the conventional optical disc drive, the sliding rails 31 and 32 are weighted with the tray 12 while the tray 12 is being ejected from the housing 10, and thus must be formed to a predetermined thickness. Also, the fixed guides 33 and 34, which are fixed on the lower case 18, are generally made of a plastic material so as to reduce noise due to friction between the fixed guides 33 and 34 and the sliding rails 31 and 32. Therefore, each of the fixed guides 33 and 34 must be formed to a predetermined thickness, usually at least 1 mm, so that they do not deform when they are loaded with the sliding rails 31 and 32. Considering the structure of the tray guide mechanism as described above, the sliding rails 31 and 32 and the fixed guides 33 and 34 must conform to a predetermined thickness in order to keep their shape, and thus there is a limitation in size of the conventional optical disc drive.
Further, the fixed guides 33 and 34, the sliding rails 31 and 32 and the rail combiners 29 and 30 glide to engage with one another when the tray 12 is inserted into the optical disc drive, which requires a predetermined interval therein. In the predetermined interval, the tray 12 may sway from side to side or upward and downward, due to vibration from a rotation of the disc and the spindle motor 26, or impact from outside of the optical disk drive. The swaying of the tray 12 may result in errors in reading data stored by the optical pickup unit 23.
FIGS. 4A through 4C are views of a mechanism that is designed to prevent the swaying of a tray 42, disclosed in U.S. Pat. No. 6,151,285 issued on Nov. 21, 2000 to Watanabe et al. Referring to FIG. 4A, one end of a holding unit 43 having a roller 45 is fixed along a sidewall 41 of a chassis (i.e., a lower case of a housing). An arm 46 of the holding unit 43 functions as a plate spring, and the roller 45 rolls along a side 42a of a tray 42 when the tray 42 moves backward and forward in directions C and D. As shown in FIG. 4A, if the tray 42 is completely inserted into a housing (not shown), the roller 45 falls into a concaved portion 42f formed at a front end of the tray 42, thus preventing movement of the tray 42 in the direction C. As a result, the tray 42 does not sway backward and forward. The roller 45 presses the side 42a of the tray 42 in a direction E due to an elastic force of the arm 46 thus, preventing the tray 42 from swaying side to side.
Referring to FIG. 4B, while the tray 42 is ejected from the housing, the roller 45 rolls along the side 42a of the tray 42, pressing the tray 42 in the direction E, thereby preventing the tray 42 from swaying from side to side.
Referring to FIG. 4C, once the tray 42 is completely ejected from the housing, the roller 45 falls into a concaved portion 42g at a rear end of the tray 42, thereby preventing movement of the tray 42 in the direction D. Further, the tray 42 does not sway backward and forward. Also, the roller 45 presses the side 42a of the tray 42 in the direction E, thus preventing the tray 42 from swaying from side to side.
However, the holding unit 43 suppresses the swaying of the tray 42 only in a horizontal direction and not in a vertical direction. Also, the holding unit 43 is positioned above the tray guide mechanism so as not to collide with the tray guide mechanism that guides the tray 42 to move backward and forward, thus increasing a height of the disc drive. Therefore, the above described mechanism as disclosed in U.S. Pat. No. 6,151,285, may prevent the swaying of the tray 42, but does not reduce the size of the optical disc drive.